The present invention relates to an improved construction for a compound bow.
Historically, the force required to draw a bow progressively increased until it reached a maximum at full draw. Thus, an archer was required to expend the maximum effort to maintain the bow at full draw during the period of time required to effect final aim just prior to release.
A number of bow constructions have been advanced by which the draw weight peaks at a point prior to full draw and then reduces to a lesser value at full draw. This permits the archer to hold the bow at full draw with less physical strain. In addition, the flight characteristics of an arrow shot from such a bow are improved because the full magnitude of the impelling force is not applied to the arrow until after it begins its forward movement.
The earliest attempts to provide a compound bow appear to have employed eccentric cranks or pulleys mounted on the tips of the limbs. This unduly increased the mass and therefore the inertia of the limbs resulting in the necessity to greatly stiffen and shorten the limbs in order to reduce the distance through which the limbs tips were required to travel and thereby minimize the adverse effects of the increased mass and inertia. However, with the stiffness of the limbs being increased in conjunction with their being shortened, a complex bow string arrangement was required to provide the mechanical advantage necessary to draw the bow.
At least one variation of prior art compound bows employs a limb in the form of a first degree lever -- each limb being secured to a handle, or center section (often designated as the riser) by virtue of a pivotal fulcrum. The outboard end of the limbs are joined by a bow string, and the inboard end of each limb engages a spring member that extends beyond the respective opposite ends of the handle section.
These prior known constructions are not only quite cumbersome but must usually be custom-made in order to provide the final draw weight desired by an archer for his particular draw length. The necessity for having to custom make such bows becomes more readily apparent when one appreciates that the draw length can vary as much as twelve inches from individual to individual depending upon each persons size and arm length.